External fold rear-view mirrors for motor vehicles are known in the art comprising a base member intended to be secured to a vehicle body and a mirror housing for receiving a mirror fitted therein. The mirror housing can be rotated, manually and/or through an electric motor and transmission means, relative to the base member between a mirror operative condition, or driving position, in which the mirror projects from the vehicle body, and a mirror folded condition, or parking position, in which the mirror housing is folded towards the vehicle body such that the distance by which the mirror housing projects from the vehicle body is reduced, and vice versa.
Locking means are also typically provided for holding the mirror housing in said driving and parking positions or even in other different specific angular positions. The locking means may be for example a detent mechanism comprising detent elements formed in the mirror housing and in the base member, respectively, adapted for locking the mirror housing in said specific angular positions. Rear-view mirrors are subject to strong temperature variations, which range from −40° C. to 80° C., and a high number of folding and unfolding cycles. As a result, materials employed for manufacturing a means for driving the mirror in rotation comprising a ring gear assembly need to have little or no dimensional variations during the product life to ensure correct operation. Thus, typically said driving means, and specially the ring gear assembly, are made of a metallic material, such as zamak. However, these materials are hard and locking means have to be designed accordingly so as to avoid wearing out during product life. Otherwise, the specific angular positions vary over time resulting in maladjustment between the base member and the mirror housing.
Depending on the external appearance of the base member and the mirror housing, clearances between both may become even visible.
ES2166677 discloses a driving mechanism for rear-view mirrors in motor vehicles. The automatic driving mechanism comprises a base member to be secured to a vehicle body, a mirror housing having a mirror fitted therein and motor means and driving means for driving the mirror housing in rotation relative to the base member between said driving and parking positions. The motor means and driving means are housed in a motor housing that is attached to the mirror housing. Said mirror housing positions are defined by teeth formed in the base member and the mirror housing forming a detent mechanism as mentioned above. Position fixing means are provided comprising a spring biased rod that is arranged in a recess in the motor housing to act radially against a stop surface formed in a groove in one of a number of grooves formed in a ring gear assembly that is part of the driving means.
The rod has to be made of a suitable material to limit wearing to acceptable tolerances so as to avoid variation of the specific angular positions during product life, which in turn leads to the motor housing having also to be made of a suitable material to avoid wearing of the recess in which the rod is arranged. In practice, this means that the rod and the motor housing are made of metal. Therefore, in order to avoid the positioning problem, the driving means, position fixing means and motor housing have to be made of metal, which lead to a cost and weight increase, entailing other known problems such as vibration and higher electric power consumption. A fold rear-view mirror assembly for motor vehicles is provided herein which has been shown to solve this technical problem.